implemented zbb instructions (logic-not, min/max, sign/zero ext)

src/Instruction_Decode/Instruction_Decode.sv

@@ -143,6 +143,7 @@ module Instruction_Decode
     , .funct7        ( funct7        )
     , .opcode        ( opcode        )
     , .rd            ( rd            )
+    , .rs2           ( rs2           )
     , .b_alu_control ( b_alu_control )
     );
 

src/ext/b/decoder.sv

@@ -5,13 +5,17 @@ module ext__b__decoder
   , input [6:0] funct7
   , input [6:0] opcode
   , input [4:0] rd
+  , input [4:0] rs2
   , output ext__b__types::b_alu_control_t b_alu_control
   );
 
   import ext__b__types::*;
 
   localparam bit [6:0] FUNCT7_ZBA = 7'b0010000;
-  localparam bit [6:0] FUNCT7_ZBB = 7'b0100000;
+  localparam bit [6:0] FUNCT7_ZBB__LOGICAL = 7'b0100000;
+  localparam bit [6:0] FUNCT7_ZBB__MINMAX = 7'b0000101;
+  localparam bit [6:0] FUNCT7_ZBB__SEXT = 7'b0110000;
+  localparam bit [6:0] FUNCT7_ZBB__ZEXT = 7'b0000100;
 
   always_comb
     case (opcode)
@@ -25,19 +29,47 @@ module ext__b__decoder
               default: b_alu_control = B_ALU_CTRL__NONE;
             endcase
 
-          FUNCT7_ZBB:
+          FUNCT7_ZBB__LOGICAL:
             case (funct3)
               3'b111:  b_alu_control = B_ALU_CTRL__ANDN;
               3'b110:  b_alu_control = B_ALU_CTRL__ORN;
               3'b100:  b_alu_control = B_ALU_CTRL__XNOR;
               default: b_alu_control = B_ALU_CTRL__NONE;
             endcase
-
+          FUNCT7_ZBB__MINMAX:
+            case (funct3)
+              3'b100:  b_alu_control = B_ALU_CTRL__MIN;
+              3'b110:  b_alu_control = B_ALU_CTRL__MAX;
+              default: b_alu_control = B_ALU_CTRL__NONE;
+            endcase
+          FUNCT7_ZBB__ZEXT:
+            case (funct3)
+              3'b100:
+                case (rs2)
+                  5'b00000: b_alu_control = B_ALU_CTRL__ZEXTH;
+                  default: b_alu_control = B_ALU_CTRL__NONE;
+                endcase
+              default: b_alu_control = B_ALU_CTRL__NONE;
+            endcase
           // TODO: Implement zbs into ALU decoder, also confirm what zbb instructions are being implemented.
           default: b_alu_control = B_ALU_CTRL__NONE;
 
         endcase
+      7'b0010011:
+        case (funct7)
+          FUNCT7_ZBB__SEXT:
+            case (funct3)
+              3'b001:
+                case (rs2)
+                  5'b00100:  b_alu_control = B_ALU_CTRL__SEXTB;
+                  5'b00101:  b_alu_control = B_ALU_CTRL__SEXTH;
+                  default: b_alu_control = B_ALU_CTRL__NONE;
+                endcase
+              default: b_alu_control = B_ALU_CTRL__NONE;
+            endcase
+          default: b_alu_control = B_ALU_CTRL__NONE;
 
+        endcase
       default: b_alu_control = B_ALU_CTRL__NONE;
     endcase
 

src/ext/b/types.svh

@@ -11,6 +11,11 @@ package ext__b__types;
     , B_ALU_CTRL__ANDN   = 4'b0100
     , B_ALU_CTRL__ORN    = 4'b0101
     , B_ALU_CTRL__XNOR   = 4'b0110
+    , B_ALU_CTRL__MIN   = 4'b0111
+    , B_ALU_CTRL__MAX   = 4'b1000
+    , B_ALU_CTRL__SEXTB   = 4'b1001
+    , B_ALU_CTRL__SEXTH   = 4'b1010
+    , B_ALU_CTRL__ZEXTH   = 4'b1011
     } b_alu_control_t;
 
 endpackage;

src/ext/b/zbb.sv

@@ -0,0 +1,26 @@
+`include "src/ext/b/types.svh"
+
+module zbb(
+    input [31:0] a
+  , input [31:0] b
+  , input ext__b__types::b_alu_control_t b_alu_control
+  , output reg [31:0] out
+  , output zeroE
+  );
+
+  always_comb
+    case (b_alu_control)
+      B_ALU_CTRL__ANDN: out = a & ~b; //andn
+      B_ALU_CTRL__ORN: out = a | ~b; //orn
+      B_ALU_CTRL__XNOR: out = ~(a ^ b); //xnor
+      B_ALU_CTRL__MIN: out = ($signed(a) < $signed(b) ? a : b); //min
+      B_ALU_CTRL__MAX: out = ($signed(a) < $signed(b) ? b : a); //max
+      B_ALU_CTRL__SEXTB: out = { {24{a[7]}}, a[7:0]}; //sext.b (sign extend byte)
+      B_ALU_CTRL__SEXTH: out = { {16{a[15]}}, a[15:0]}; //sext.h (sign extend halfword)
+      B_ALU_CTRL__ZEXTH: out = {16'b0, a[15:0]}; //zext.h (zero extend halfword)
+      default: out = 32'd0; //other
+    endcase
+
+  assign zeroE = (out == 0);
+
+endmodule